migrate to decoupled Blowfish layout, fix TOC scrollspy, and update docs

- Theme Decoupling & Cleanup:
      - Fully decoupled and vendored the Blowfish theme directly into root directories (layouts/,
  assets/, static/, data/, i18n/).
      - De-registered and cleaned up legacy Git submodules (themes/blowfish, themes/hugo-admonitions)
  from the Git index to protect the build from upstream breakages.
      - Configured .gitignore to ignore development preview symlinks (content, static,
  config/_default/menus.en.toml), build folders (public/, resources/), and locks.

    - TOC & Layout Fixes:
      - Replaced the custom layouts/_default/single.html template with the Blowfish default to restore
  native container widths and the side-by-side flex layout.
      - Restored TOC to float on the right sidebar on desktop viewports and render inline on mobile
  viewports.
      - Fixed a parameter resolution bug in layouts/partials/toc.html by checking both .Site.Params.
  smartTOC and .Site.Params.article.smartTOC (where it is defined in params.toml).
      - Upgraded the TOC scrollspy JavaScript to target all '#TableOfContents' containers on the page,
  enabling highlight tracking on both desktop and mobile layouts.

    - Documentation Updates (README.md):
      - Restored YAML front matter metadata block at the top.
      - Added detailed notes on the CI/CD build process and Gitea runner deployment targets
  (/srv/www/docs-public and /srv/www/docs-private).
      - Added a categorized and sorted "Shortcodes Quick Reference" table at the top of the shortcodes
  section (ordered by Custom, Hugo Default, and Blowfish).
      - Documented custom shortcodes (Include, Screenshot, Raw HTML) and missing Hugo default
  shortcodes (Highlight, Instagram, Param, Ref, Relref, Twitter, Vimeo, Youtube).
      - Restructured headings to ensure all sub-shortcodes are H3, removed block break tags (<br/>),
  and appended horizontal separators (---) after H2 sections.

assets/js/a11y.js

@@ -0,0 +1,170 @@
+window.A11yPanel = (() => {
+  const FEATURES = {
+    disableBlur: {
+      default: false,
+      apply: (enabled) => {
+        document.querySelectorAll("script[data-blur-id]").forEach((script) => {
+          const targetId = script.getAttribute("data-blur-id");
+          const scrollDivisor = Number(script.getAttribute("data-scroll-divisor") || 300);
+          if (typeof setBackgroundBlur === "function") {
+            setBackgroundBlur(targetId, scrollDivisor, enabled, targetId === "menu-blur");
+          }
+        });
+      },
+    },
+
+    disableImages: {
+      default: false,
+      apply: (enabled) => {
+        const image = document.getElementById("background-image");
+        if (image) {
+          image.style.display = enabled ? "none" : "";
+        }
+      },
+    },
+
+    fontSize: {
+      default: "default",
+      apply: (size) => {
+        document.documentElement.style.fontSize = size === "default" ? "" : size;
+      },
+    },
+
+    underlineLinks: {
+      default: false,
+      apply: (enabled) => {
+        const existing = document.getElementById("a11y-underline-links");
+        if (enabled && !existing) {
+          const style = document.createElement("style");
+          style.id = "a11y-underline-links";
+          style.textContent = `
+            a { text-decoration: underline !important; }
+            .group-hover-card-title { text-decoration: underline !important; }
+            .group-hover-card:hover .group-hover-card-title { text-decoration: underline !important; }`;
+          document.head.appendChild(style);
+        } else if (!enabled && existing) {
+          existing.remove();
+        }
+      },
+    },
+
+    zenMode: {
+      default: false,
+      apply: (enabled) => {
+        const isActive = document.body?.classList.contains("zen-mode-enable");
+        if (enabled !== isActive) {
+          const checkbox = document.querySelector('[id$="zen-mode"]');
+          if (checkbox && typeof _toggleZenMode === "function") {
+            _toggleZenMode(checkbox, { scrollToHeader: false });
+          }
+        }
+      },
+    },
+  };
+
+  let settings = null;
+
+  const getSettings = () => {
+    if (settings) return settings;
+    const defaults = Object.fromEntries(Object.entries(FEATURES).map(([key, config]) => [key, config.default]));
+    try {
+      const saved = localStorage.getItem("a11ySettings");
+      settings = { ...defaults, ...JSON.parse(saved || "{}") };
+    } catch {
+      settings = defaults;
+    }
+    return settings;
+  };
+
+  const updateSetting = (key, value) => {
+    const current = getSettings();
+    current[key] = value;
+    try {
+      localStorage.setItem("a11ySettings", JSON.stringify(current));
+    } catch (e) {
+      console.warn(`a11y.js: can not store settings: ${e}`);
+    }
+    FEATURES[key]?.apply(value);
+  };
+
+  const initPanel = (panelId) => {
+    const prefix = panelId.replace("a11y-panel", "");
+    const current = getSettings();
+
+    Object.entries(FEATURES).forEach(([key, config]) => {
+      const elementId = `${prefix}${key.replace(/([A-Z])/g, "-$1").toLowerCase()}`;
+      const element = document.getElementById(elementId) || document.getElementById(`${elementId}-select`);
+
+      if (element) {
+        if (element.type === "checkbox") {
+          element.checked = current[key];
+          element.onchange = (e) => updateSetting(key, e.target.checked);
+        } else if (element.tagName === "SELECT") {
+          element.value = current[key];
+          element.onchange = (e) => updateSetting(key, e.target.value);
+        }
+      }
+    });
+
+    const togglePanel = () => {
+      const panel = document.getElementById(panelId);
+      const overlay = document.getElementById(`${prefix}a11y-overlay`);
+      const toggle = document.getElementById(`${prefix}a11y-toggle`);
+
+      if (!panel || !overlay) return;
+
+      const isHidden = overlay.classList.contains("hidden");
+      overlay.classList.toggle("hidden");
+      panel.classList.toggle("hidden");
+
+      if (toggle) {
+        toggle.setAttribute("aria-pressed", String(isHidden));
+        toggle.setAttribute("aria-expanded", String(isHidden));
+      }
+    };
+
+    const toggle = document.getElementById(`${prefix}a11y-toggle`);
+    const close = document.getElementById(`${prefix}a11y-close`);
+    const overlay = document.getElementById(`${prefix}a11y-overlay`);
+
+    if (toggle) toggle.onclick = togglePanel;
+    if (close) close.onclick = togglePanel;
+    if (overlay) overlay.onclick = (e) => e.target === overlay && togglePanel();
+  };
+
+  const applyAll = () => {
+    const current = getSettings();
+    Object.entries(current).forEach(([key, value]) => {
+      FEATURES[key]?.apply(value);
+    });
+  };
+
+  const init = () => {
+    applyAll();
+    document.querySelectorAll('[id$="a11y-panel"]').forEach((panel) => {
+      initPanel(panel.id);
+    });
+  };
+
+  if (getSettings().disableImages) {
+    new MutationObserver(() => {
+      const img = document.getElementById("background-image");
+      if (img) img.style.display = "none";
+    }).observe(document, { childList: true, subtree: true });
+  }
+
+  if (document.readyState === "loading") {
+    document.addEventListener("DOMContentLoaded", init);
+  } else {
+    init();
+  }
+
+  return {
+    getSettings,
+    updateSetting,
+    addFeature: (name, config) => {
+      FEATURES[name] = config;
+      FEATURES[name].apply(getSettings()[name] || config.default);
+    },
+  };
+})();